The rates of 12 obesity-related cancers rose by 7 percent from 2005 to 2014, an increase that is threatening to reverse progress in reducing the rate of cancer in the United States, U.S. health officials said on Tuesday.
According to the U.S. Centers for Disease Control and Prevention, more than 630,000 people in the United States were diagnosed with a cancer linked with being overweight or obese in 2014.
Obesity-related cancers accounted for about 40 percent of all cancers diagnosed in the United States in 2014. Although the overall rate of new cancer diagnoses has fallen since the 1990s, rates of obesity-related cancers have been rising.
"Today's report shows in some cancers we're going in the wrong direction," Dr. Anne Schuchat of the CDC said on a conference call with reporters.
According to the International Agency for Research on Cancer, 13 cancers are associated with overweight and obesity.
They include meningioma, multiple myeloma, adenocarcinoma of the esophagus, and cancers of the thyroid, postmenopausal breast, gallbladder, stomach, liver, pancreas, kidney, ovaries, uterus and colon and rectum (colorectal).
In 2013-2014, about two out of three U.S. adults were considered overweight or obese. CDC researchers used the U.S. cancer statistics database to see how obesity was affecting cancer rates.
Although cancer rates rose in 12 of these cancers from 2005 to 2012, colorectal cancer rates fell by 23 percent, helped by increases in screening, which prevents new cases by finding growths before they turn into cancer.
Cancers not associated with overweight and obesity fell by 13 percent.
About half of Americans are not aware of this link, according to Schuchat. The findings suggest that U.S. healthcare providers need to make clear to patients the link between obesity and cancer, and encourage patients to achieve a healthy weight.
"The trends we are reporting today are concerning," Schuchat said. "There are many good reasons to strive for a healthy weight. Now you can add cancer to the list."
She said the science linking cancer to obesity is still evolving, and it is not yet clear whether losing weight will help individuals once cancer has taken root.
What is clear is that obesity can raise an individual's risk of cancer, and that risk may be reduced by maintaining a healthy weight, Schuchat said.